This section provides background information related to the present disclosure and is not necessarily prior art.
A compressor is one of the most important pieces of equipment used in an HVAC (Heating, Ventilation and Air-Conditioning) system. Compressors are used to control the circulation of refrigerant within the HVAC system, by drawing in refrigerant at low pressure and low temperature and delivering it at a higher pressure and temperature to the system. Depending on the capacity requirements of HVAC applications, different compressors are used such as reciprocating and rotary, including scroll compressors, screw compressors, and the like.
Reciprocating compressors typically have one or more pistons that are used to compress refrigerant to increase its pressure. Reciprocating compressors use the reciprocating action of a piston inside a cylinder to compress refrigerant. The piston is driven up/down or back/forth by a crankshaft. The cylinder includes an inlet and an outlet for entry of refrigerant and exit of compressed refrigerant respectively. Refrigerant entering the cylinder through the inlet is compressed by an upward movement of the piston in the cylinder. As the piston is driven upward in the cylinder, refrigerant in the cylinder is compressed prior to exiting out of the cylinder through the outlet when the required compression pressure has been achieved.
Scroll compressors include two disks, each including a spiral wrap. The spiral wraps of the two disks are nested together, wherein a first disk is stationary and a second disk is moving around the first in an orbital fashion. Refrigerant is sucked in through an inlet typically located at the perimeter of the nested disk arrangement and gets trapped in a space between the two nested disks. As the second disk moves in relation to the first disk, refrigerant in the space between the disks is compressed and reaches a high pressure and temperature. Compressed refrigerant is then discharged through an outlet typically located at the center of the first disk.
Compressed refrigerant then enters a piping system for being transported to other equipment connected to the compressor of the HVAC system where it is needed. The aforementioned methods of operation cause compressed refrigerant to be delivered to the piping system or other equipment in pulses instead of a continuous flow. As a result, compressed refrigerant, when being discharged into a small volume such as a short pipe, can cause pressure fluctuations in the associated piping system. Several undesirable effects of pressure fluctuations appear in the piping system and/or the equipment connected to the compressor or within the compressor itself. All of these undesirable effects are due to discharge pulsations which appear as a result of the pulsating action of the compressing means such nested disks, a piston, or the like. A major drawback which arises from discharge pulsations is the effect of vibration such as rattling which appears in the piping system and/or other equipment connected to the compressor, and can potentially damage the piping system and/or the equipment connected to the compressor. When the discharge pulsations are severe, the vibration/rattling is frequently accompanied by considerable noise, which radiates from the piping system. Severe discharge pulsations can also considerably decrease the efficiency of the compressor.
In order to absorb or dampen the pressure fluctuations, an oversized piping system is typically used. However, an oversized piping system results in heavier pipes, which can lead to maintenance issues and cost escalation. Another alternative is to provide a discharge cavity at the outlet of the compressing means whereby the volume of the cavity facilitates a reduction in the discharge pulsations. However, in order to provide a discharge cavity, the size of the shell/housing of the compressor needs to be increased, thereby making the compressor heavy, large, and difficult to service. Additionally, a discharge muffler is typically coupled to the outlet of the compressor to attenuate discharge pulsations generated by the compressor. However, acoustic characteristics of the discharge muffler are extremely important in achieving efficient pulsation dampening. Furthermore, existing discharge mufflers may share a large partition with the suction/inlet portion of the compressor. The high temperature of the discharge muffler can transfer heat to the inlet portion of the compressor and decrease the efficiency of the compressor.
Hence, there is a need for a mechanism that can effectively dampen discharge pulsations while occupying less space and increasing the efficiency of the compressor.